1. Field of the Invention
Aspects of the present invention relate to a machine vision apparatus for locating features on an object using varied illumination.
2. Description of Background Information
A vision tool exists that measures the area and location of solder paste printed on circuit boards for the purpose of inspecting the prints made for solder paste screen print machines. An apparatus compares a pre-print image of a circuit board at a given inspection site with a post-print image of the circuit board at the given inspection site to determine which pixels in the post-print image represent solder paste. The identified pixels are then grouped into regions and measured by a xe2x80x9cblobxe2x80x9d tool.
A main limitation of the above apparatus is that two images of each inspection site of each circuit board must be acquiredxe2x80x94a before printing image and an after printing image. Moving the camera from inspection site to inspection site and visiting each site twice takes time and reduces the throughput of the apparatus.
In an embodiment of the invention, an apparatus is provided for locating features of an object using varied lighting. The apparatus includes an image processor which is configured to send a plurality of commands to a digital camera which is used to obtain a plurality of digital images of an object without moving a location of the digital camera and the object. The image processor is arranged to receive the digital images of the object from the digital camera and the image processor is configured to control a level of illumination from at least one light source for illuminating the object. The image processor includes an illumination changer, a subtracter, an analyzer, and a controller to control and coordinate the illumination changer, the subtracter, and the analyzer. The illumination changer changes a level of illumination of any of the at least one lighting source before the image processor sends a command to the digital camera to obtain a next digital image. The subtracter subtracts at least a second digital image of the object from a first digital image of the object to produce a difference image of the object. The analyzer analyzes the difference image and locates at least one feature of the object based on the difference image.